[linux-audio-dev] next power of two

[Jack O'Quin]

Taybin Rutkin <taybin at earthlink.net> writes:

> Heh, that doesn't sound very RISC-like to me...

He called them "functions", not "instructions".  I don't recall any
such instructions back back when I worked on PowerPC.  But, providing
fast subroutine linkage for stuff like this is *very* RISC-like.  It's
really fundamental to the RISC approach.

Many people misunderstand RISC.  The goal is not to "reduce" the
number of instructions.  PowerPC has *lots* of instructions.  The
intent is to reduce the time required for all the frequently-used
instructions to one fast clock cycle.

Please forgive the long-winded reply, Taybin.  I worked on this stuff
for many years, and I still love it.  :-)

> -----Original Message-----
> From: Maarten de Boer <mdeboer at iua.upf.es>
> Sent: Sep 18, 2003 7:41 AM
> To: linux-audio-dev at music.columbia.edu
> Subject: Re: [linux-audio-dev] next power of two
> 
> By the way, it seems the PPC has instructions to do it.
> >From the "PPC compiler writers guide":
> 
> Round Up or Down to Next Power of 2
> 
> The floor power of 2 ( flp2) and ceiling power of 2 ( clp2) functions
> are similar to the floor and ceiling functions, respectively, but they
> round to an integral power of 2, rather than to an integer.
> 

Regards,
-- 
  Jack O'Quin
  Austin, Texas, USA